{"id":600,"date":"2008-09-18T17:12:52","date_gmt":"2008-09-18T22:12:52","guid":{"rendered":"http:\/\/www.realclimate.org\/index.php\/archives\/2008\/09\/on-straw-men-and-greenland-tad-pfeffer-responds\/"},"modified":"2008-09-23T09:42:27","modified_gmt":"2008-09-23T14:42:27","slug":"on-straw-men-and-greenland-tad-pfeffer-responds","status":"publish","type":"post","link":"https:\/\/www.realclimate.org\/index.php\/archives\/2008\/09\/on-straw-men-and-greenland-tad-pfeffer-responds\/","title":{"rendered":"On straw men and Greenland: Tad Pfeffer Responds"},"content":{"rendered":"
\n


\nIn a recent post<\/a> about sea level rise, we highlighted a paper by the University of Colorado’s Tad Pfeffer and others in which they show that one can rule out more than 2 meters of sea level rise in the next century. While we liked the paper very much, we also complained that Pfeffer and colleagues had created a bit of a straw man, by implying that it had been seriously proposed that Greenland’s near term contribution to sea level rise could be much larger than that. In fact (we said), none of us in the climate science community ever took such ideas seriously, even if the popular press thought we did. Tad responds by pointing out that in fact there is<\/i> published work attributing considerable likelihood to such extreme scenarios, and that there are numerous studies that at the very least strong imply it. He also reminded me that their paper actually rules out a contribution of more than about 50 cm from Greenland, significantly below some other recent published estimates. That makes their work even more important, since there are several publications that definitely consider upwards of one meter (from Greenland alone) by 2100 to be plausible. Pfeffer et al. conclude that that is simply not the case (at least in their informed view). Still, we remind readers that our chief complaint was that Pfeffer et al.’s work was taken by many in the media as a downward revision to sea level rise estimates, whereas in fact most informed estimates had put an upper limit well below that. See our earlier post on the IPCC Sea Level numbers<\/a>.<\/p>\n

In any case. Pfeffer et al’.s response to our post follows below. Fair enough.<\/p>\n

<\/small><\/p>\n

\nA response to RealClimate\u2019s post on our paper about sea level rise<\/b>
\n
W.T. Pfeffer, J.T. Harper, and S. O\u2019Neel
15 September 2008<\/p>\n

We have read with interest \u2013 and, we admit, surprise \u2013 the RealClimate post<\/a> concerning our 5 September publication in Science entitled \u201cKinematic Constraints on 21st Century Sea Level Rise.\u201d The source of our surprise, however, is probably not what the RealClimate authors imagine \u2013 we had fully expected a vigorous defense of very high rates of sea level rise (greater than 2 m\/century), but not a denial that such rates had ever been hypothesized. <\/p>\n

We do not state anywhere in our paper that 2m or more of SLR by 2100 has been published as a peer reviewed and \u201cinformed estimate\u201d. We do state that this has been \u2018inferred\u2019 and \u2018argued\u2019 as a \u201cviable 21st century scenario\u201d. We believe there is value in constraining the upper limits to the role of ice dynamics in future SLR. And, from what we know about historical rates of SLR in conjunction with what \u2018we know we don\u2019t know\u2019 about ice dynamics, we believe it is reasonable to ponder very high rates of SLR in the next century. However, we also believe that it is problematic to project such a \u2018hypothesis\u2019 as a supported theory without proper testing by the scientific method. The question raised by RC is whether or not this hypothesis has circulated within the scientific community.<\/p>\n

In his 2007 paper (Environ. Res. Lett. 2(2007)) Hansen proposes a rate of sea level rise of \u201c5 m this century.\u201d This is hypothetical, but he is confident that it is a \u201cfar better estimate than a linear response\u201d. This is accompanied by his statement that he finds it \u201calmost inconceivable that BAU climate change would not yield a sea level change of the order of meters on the century timescale.\u201d The provisional nature of his discussion is irrelevant; it is an explicit statement that 5 m of sea level rise in this century is a possibility he regards as viable, published in the scientific literature by the person who is arguably (and deservedly) the most visible and authoritative climate scientist in the world. No reader of this paper would assume that Hansen didn\u2019t actually mean what he said. Hansen reinforced this idea in other publications and statements, including in his briefing to Congress on 23 June 2008 (\u201csea level rise of at least two meters is likely this century\u201d). Our analysis specifically tested the likelihood of next-century sea level rise of more than 2 m, and Hansen explicitly hypothesized 5 m of sea level rise in this century. <\/p>\n

Hansen has gone on record with specific numbers, but other published studies including the 2006 Overpeck and Otto-Bliesner Science papers left the upper limit open ended, and certainly implied it could be quite high. The fact that this idea was present in the scientific community was confirmed for us by 8 scientific presentations we gave on this topic in the past year (5 in the US, including the Fall 2007 AGU and 3 in Europe). At none of those talks did anyone in the audience question what high forecasts we were referring to. The comments we got back on our work were overwhelmingly positive, and were along the lines that what we had presented was a good next step \u2013 both to move past the IPCC\u2019s low sea level forecasts, and as a response to the persistent hypotheses of very high rates of sea level rise that were circulating. Criticisms, where they were voiced, were largely that we were underestimating the power of dynamics and that rates of sea level rise well in excess of 2 m\/century might occur in spite of our conclusions.<\/p>\n

We agree that the media coverage of our paper (as well as others before it) has undesirable side effects. Wherever we had the opportunity we pressed media writers not to use terms like \u201cexaggerated\u201d or \u201chigh sea level forecasts debunked,\u201d and we have consistently stressed that our results indicate a very significant sea level rise and are no justification for any kind of complacency. We have stressed that even our low end scenario of 0.8 m of SLR would have tremendous consequences. However, we stand by our statements that sea level rise at rates of substantially more than 2 m this century were in fact put forward as a likely possibility. <\/p>\n

Earlier this summer Andy Revkin published a piece in the New York Times about what he has termed the \u201cWhiplash Effect\u201d: confusion created in the public mind by media coverage of rapidly evolving scientific ideas. There has certainly been some whiplash in this case. However it is others who cracked the whip. We have simply refused to let go of the other end.<\/p>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

In a recent post about sea level rise, we highlighted a paper by the University of Colorado’s Tad Pfeffer and others in which they show that one can rule out more than 2 meters of sea level rise in the next century. While we liked the paper very much, we also complained that Pfeffer and […]<\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[1],"tags":[],"class_list":{"0":"post-600","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-climate-science","7":"entry"},"aioseo_notices":[],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts\/600","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/comments?post=600"}],"version-history":[{"count":0,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts\/600\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/media?parent=600"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/categories?post=600"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/tags?post=600"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}